1. Field of the Invention
The present invention relates to a technique for making acoustic characteristics of a speaker appropriate.
2. Description of Related Art
There is known a speaker having: an enclosure in the form of a box-like member; and one or a plurality of speaker units each of which is fixed to a plate of the enclosure that forms a front face of the enclosure, such that a sound emission surface of each speaker unit is oriented frontward of the speaker. The plate of the speaker to which each speaker unit is fixed is called a baffle plate. In such a speaker, sounds emitted in a frontward direction from each speaker unit are diffracted, and the diffracted sounds are reflected at various points on the baffle plate, so that the sounds reflected at various points are again emitted in the frontward direction. Consequently, there are transmitted, to listening points located frontward of the speaker, not only direct sounds emitted from the speaker units, but also the sounds diffracted after emission from the speaker units in the frontward direction and again emitted after reflection at various points on the baffle plate. Accordingly, peaks and dips occur in a frequency response of each of acoustic transmission systems from the speaker units to the listening points, undesirably causing a risk of deterioration in acoustic characteristics. In an attempt to solve the problem, the following Patent Literature 1 discloses a speaker system in which a sound absorbing member is attached to the periphery of a speaker unit on a front-face baffle of an enclosure. In the disclosed speaker system, sound waves diffracted sideways from the speaker unit are absorbed by the sound absorbing member on the front-face baffle, whereby the sound pressure of the sounds reflected in the frontward direction is reduced. According to the disclosed technique, acoustic characteristics at listening points located frontward of the speaker system can be prevented from being deteriorated.    Patent Literature 1: JP-A-2009-94706